A hybrid vehicle typically utilizes several sources of energy which are selectively and alternatively adapted to generate torque which is transferred to the wheels of the vehicle. At least one of these energy sources typically comprises, by way of example and without limitation, an electrical battery assembly which must be periodically "recharged" in combination with an electric motor. The second source of torque usually comprises an internal combustion engine which is typically adapted to generate and communicate torque to the wheels while selectively recharging the battery assembly when the state of charge of the battery assembly (i.e., the amount of electrical charge contained within the battery assembly) falls below a certain threshold value.
Each source of energy typically transfers the respectively produced torque to the vehicle wheels with a certain efficiency which is dependent upon several operating attributes of the vehicle (i.e., the speed of the vehicle). For instance, the internal combustion engine efficiently transfers torque to the wheels at relatively high speeds. However, the torque transfer efficiency of the internal combustion engine is reduced when it is also selectively charging the battery assembly.
A hybrid vehicle does not include an apparatus or employ a method to select one of several energy sources in a manner which is effective to ensure efficient torque transfer operation and does not include an apparatus or a method to operate the selected energy source (e.g., the internal combustion engine) in a manner which further ensures efficient operation and efficient torque transfer, thereby undesirably and unnecessarily wasting a portion of the generated energy.
There is therefore a need for a method and an apparatus for selecting an energy source and for transferring torque in a hybrid vehicle which overcomes at least some of the previously delineated drawbacks of prior hybrid vehicles and which, by way of example and without limitation, allows the generated torque to be efficiently transferred to the wheels of the vehicle.